There are many potential uses for graft polymers having halobutyl rubber backbones. For instance, chlorobutyl rubber which has low air permeability and outstanding age resistance is incompatible with most rubbers commonly utilized in building tires. Chlorobutyl rubber is accordingly a highly desirable rubber for incorporation into tire compounds but is very difficult to cocure with other rubbers utilized in the tire compound. By grafting a polydiene rubber, such a polybutadiene, onto chlorobutyl rubber, the chlorobutyl rubber is compatibilized with most common rubbers utilized in building tires and can be very effectively cocured therewith.
Heretofore, it has been very difficult, if not impossible, to synthesize graft polymers having halobutyl rubber backbones. Prior attempts to graft polystyryl lithium onto chlorobutyl rubber have all resulted in failure. Prior to the subject invention, attempts to graft sidechains which are derived from diene monomers onto halobutyl rubber backbones have also resulted in enormous difficulties.